Kcnma1 is involved in mitochondrial homeostasis in diabetes-related skeletal muscle atrophy.

Uncontrolled diabetes causes a catabolic state with multi-organic complications, of which impairment on skeletal muscle contributes to the damaged mobility. Kcnma1 gene encodes the pore-forming α-subunit of Ca2+ - and voltage-gated K+ channels of large conductance (BK channels), and loss-of-function mutations in Kcnma1 are in regards to impaired myogenesis. Herein, we observed a time-course reduction of Kcnma1 expression in the tibialis anterior muscles of leptin receptor-deficient (db/db) diabetic mice. To investigate the role of Kcnma1 in diabetic muscle atrophy, muscle-specific knockdown of Kcnma1 was achieved by mice receiving intravenous injection of adeno-associated virus-9 (AAV9)-encoding shRNA against Kcnma1 under the muscle creatine kinase (MCK) promoter. Impairment on muscle mass and myogenesis were observed in m/m mice with AAV9-shKcnma1 intervention, while this impairment was more obvious in diabetic db/db mice. Simultaneously, damaged mitochondrial dynamics and biogenesis showed much severer in db/db mice with AAV9-shKcnma1 intervention. RNA sequencing revealed the large transcriptomic changes resulted by Kcnma1 knockdown, and changes in mitochondrial homeostasis-related genes were validated. Besides, the artificial alteration of Kcnma1 in mouse C2C12 myoblasts was achieved with an adenovirus vector. Consistent results were demonstrated by Kcnma1 knockdown in palmitate-treated cells, whereas opposite results were exhibited by Kcnma1 overexpression. Collectively, we document Kcnma1 as a potential keeper of mitochondrial homeostasis, and the loss of Kcnma1 is a critical event in priming skeletal muscle loss in diabetes.

Skeletal muscle mass and function are affected by pancreatic atrophy, pancreatic exocrine insufficiency and poor nutritional status in patients with chronic pancreatitis.

BACKGROUND/OBJECTIVE: Previous studies have demonstrated that sarcopenia is frequently observed in patients with chronic pancreatitis (CP). However, most studies have defined sarcopenia solely based on skeletal muscle (SM) loss, and muscle weakness such as grip strength (GS) reduction has not been considered. We aimed to clarify whether SM loss and reduced GS have different associations with clinical characteristics and pancreatic imaging findings in patients with CP. METHODS: One hundred two patients with CP were enrolled. We defined SM loss by the SM index at the third lumbar vertebra on CT (<42 cm2/m2 for males and <38 cm2/m2 for females), and reduced GS by < 28 kg for males and <18 kg for females. RESULTS: Fifty-seven (55.9 %) patients had SM loss, 21 (20.6 %) had reduced GS, and 17 (16.7 %) had both. Patients with SM loss had lower body mass index, weaker GS, higher Controlling Nutritional Status score, lower serum lipase level, and lower urinary para-aminobenzoic acid excretion rate, suggesting worse nutritional status and pancreatic exocrine insufficiency. On CT, main pancreatic duct dilatation and parenchymal atrophy were more frequent in patients with SM loss than in those without it. Patients with reduced GS were older and had worse nutritional status than those without it. CONCLUSIONS: SM loss was associated with pancreatic exocrine insufficiency, low nutritional status, and pancreatic imaging findings such as parenchymal atrophy and main pancreatic duct dilatation, whereas older age and low nutritional status led to additional reduced GS.

Cholinesterase as a predictor of skeletal muscle loss after gastrectomy for gastric cancer.

BACKGROUND: Cholinesterase is a classical nutritional and inflammatory marker. The aim of the present study was to evaluate the value of cholinesterase as a predictive marker for postoperative skeletal muscle loss after gastrectomy for gastric cancer. METHODS: The study comprised 68 patients who had undergone gastrectomy for gastric cancer. Skeletal muscle mass was evaluated using skeletal mass index, and major skeletal muscle loss was defined as less than or equal to the median change rate (1-year postoperative/preoperative) of skeletal mass index in all patients. We explored the relationship between postoperative major skeletal muscle loss and disease-free survival and overall survival. Then we investigated the relationship between change rate of skeletal muscle index and serum cholinesterase levels after gastrectomy. RESULTS: The median value of change rate of skeletal mass index was 0.93. Postoperative major skeletal muscle loss was significantly associated with disease-free survival after gastrectomy (P = 0.003). Although major skeletal muscle loss had worse overall survival, it was not significant (P = 0.058). The change rate of skeletal mass index and cholinesterase had a stronger positive correlation compared with other nutritional indices according to Spearman's rank correlation coefficient (r = 0.438, P ≤ 0.001). CONCLUSION: Evaluation of serum cholinesterase levels may be valuable for predicting postoperative skeletal muscle loss after gastrectomy, suggesting the importance of cholinesterase in postoperative nutritional management of patients with gastric cancer.

Muscle loss phenotype in COPD is associated with adverse outcomes in the UK Biobank.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disorder with systemic consequences that can cause a muscle loss phenotype (MLP), which is characterized by the loss of muscle mass, muscle strength, or loss of both muscle and fat mass. There are limited data comparing the individual traits of MLP with clinical outcomes in a large unbiased cohort of COPD patients. Our aim was to determine the proportion of patients who met criteria for MLP in an unbiased sample of COPD patients at the population-level. We also determined if specific MLP features were associated with all-cause and COPD-related mortality. METHODS: A retrospective population-based cohort analysis of the UK Biobank was performed. COPD was defined by a FEV1/FVC ratio < 0.7, physician established diagnosis of COPD, or those with a COPD-related hospitalization before baseline assessment. MLP included one or more of the following: 1) Low fat-free mass index (FFMI) on bioelectric impedance analysis (BIA) or 2) Appendicular skeletal muscle index (ASMI) on BIA, 3) Low muscle strength defined by handgrip strength (HGS), or 4) Low muscle and fat mass based on body mass index (BMI). Cox regression was used to determine the association between MLP and all-cause or COPD-related mortality. All models were adjusted for sex, age at assessment, ethnicity, BMI, alcohol use, smoking status, prior cancer diagnosis and FEV1/FVC ratio. RESULTS: There were 55,782 subjects (56% male) with COPD followed for a median of 70.1 months with a mean(± SD) age at assessment of 59 ± 7.5 years, and FEV1% of 79.2 ± 18.5. Most subjects had mild (50.4%) or moderate (42.8%) COPD. Many patients had evidence of a MLP, which was present in 53.4% of COPD patients (34% by ASMI, 26% by HGS). Of the 5,608 deaths in patients diagnosed with COPD, 907 were COPD-related. After multivariate adjustment, COPD subjects with MLP had a 30% higher hazard-ratio for all-cause death and 70% higher hazard-ratio for COPD-related death. CONCLUSIONS: Evidence of MLP is common in a large population-based cohort of COPD and is associated with higher risk for all-cause and COPD-related mortality.

Myogenic microRNAs as Therapeutic Targets for Skeletal Muscle Mass Wasting in Breast Cancer Models.

Breast cancer is the type of cancer with the highest prevalence in women worldwide. Skeletal muscle atrophy is an important prognostic factor in women diagnosed with breast cancer. This atrophy stems from disrupted skeletal muscle homeostasis, triggered by diminished anabolic signalling and heightened inflammatory conditions, culminating in an upregulation of skeletal muscle proteolysis gene expression. The importance of delving into research on modulators of skeletal muscle atrophy, such as microRNAs (miRNAs), which play a crucial role in regulating cellular signalling pathways involved in skeletal muscle protein synthesis and degradation, has been recognised. This holds true for conditions of homeostasis as well as pathologies like cancer. However, the determination of specific miRNAs that modulate skeletal muscle atrophy in breast cancer conditions has not yet been explored. In this narrative review, we aim to identify miRNAs that could directly or indirectly influence skeletal muscle atrophy in breast cancer models to gain an updated perspective on potential therapeutic targets that could be modulated through resistance exercise training, aiming to mitigate the loss of skeletal muscle mass in breast cancer patients.

Effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced GIST.

BACKGROUND: Currently, the effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced gastrointestinal stromal tumors (LA-GIST) remains unclear. This study aims to investigate the relationship between changes in skeletal muscle and postoperative complications, survival and tumor response in patients with LA-GIST during neoadjuvant therapy with imatinib. METHODS: We retrospectively analyzed pre- and post-treatment computed tomography images of 57 GIST patients who underwent radical surgery after neoadjuvant therapy with imatinib from January 2013 to March 2019. Skeletal muscle index (SMI) was measured at the L3 vertebral level in all patients. A cut-off value (SMI < 52.3 cm2/m2 and < 38.6 cm2/m2 for men and women, respectively) published in a previous study was used to define sarcopenia. Based on gender, we defined ΔSMI (%)/250 days above 9.69% for men and ΔSMI (%)/250 days above 7.63% for women as significant muscle loss (SML). Factors associated with postoperative complications and tumor response were analyzed using logistic regression, and predictors affecting patient prognosis were analyzed using Cox regression. RESULTS: Of the 57 patients, sarcopenia was present before and after neoadjuvant therapy in 20 (35.09%) and 28 (49.12%) patients, respectively. It was not associated with immediate or long-term clinical outcomes. However, patients with SML during neoadjuvant therapy had a higher incidence of postoperative complications (60.00% vs. 25.00%, p = 0.008), worse pathological regression (44.00% vs. 75.00%, p = 0.017) and worse 3-year survival (Male, 68.75% vs. 95.45%, p = 0.027; Female, 66.67% vs. 100.00%, p = 0.046) than patients without SML. CONCLUSION: The development of SML during neoadjuvant therapy in LA-GIST patients, rather than pre- and post-treatment sarcopenia, is a major prognostic factor for the long-term prognosis and is also associated with recent postoperative complication rates and pathological regression.

Total iron binding capacity is a predictor for muscle loss in maintenance hemodialysis patients.

BACKGROUND: Protein-energy wasting in hemodialysis (HD) patients is characterized by decreased skeletal muscle mass and plasma protein. Some previous studies reported relationships between skeletal muscle dysfunction and iron deficiency. Dialysis patients with malnutrition may have a functional iron deficiency (FID) because of inflammation. Serum total iron binding capacity (TIBC), correlated with transferrin, is a nutritional status marker in HD patients and a biomarker of iron status. The relationship between muscle loss and iron status is unknown. The aim of the present study was to assess the relationship between iron status and change in skeletal muscle mass. METHODS: A prospective cohort of 267 HD patients was examined for 12 months. Blood samples were obtained at baseline to measure TIBC, ferritin, transferrin saturation (TSAT), and hepcidin-25. Nutritional status and changes in muscle mass were assessed by subjective global assessment, albumin, creatinine index, and percentage creatinine generation rate. RESULTS: At baseline, lower tertiles of TIBC were significantly related to lower muscle mass and albumin levels; they were also significantly correlated with high ferritin, hepcidin-25, and TSAT levels, as well as a higher proportion of use of erythropoiesis-stimulating agents. Multiple regression analysis adjusted with confounders showed TIBC was an independent biomarker for decreased muscle mass and albumin. Change in muscle mass remained significantly decreased in the lower tertile of TIBC and in malnourished patients. CONCLUSIONS: The present study demonstrated relationships between FID and muscle loss. TIBC was an independent biomarker of muscle loss in HD patients, considering iron status, inflammation, oxidative stress, and malnutrition.

The type of gastrectomy affects skeletal muscle loss and the long-term outcomes of elderly patients with gastric cancer: a retrospective study using computed tomography images.

PURPOSE: Sarcopenia is common in elderly gastrectomized patients and a known risk factor for postoperative complications and poor overall survival. However, the long-term outcomes of skeletal muscle loss after gastrectomy and the differences in outcomes of different gastrectomy procedures remain unclear. METHODS: The subjects of this retrospective study were 136 patients who underwent various gastrectomy procedures for early gastric cancer, namely: total gastrectomy (TG; n = 20), proximal gastrectomy (PG; n = 16), distal gastrectomy (DG; n = 60), and pylorus-preserving gastrectomy (PPG; n = 40). Skeletal muscle volume (SMV), calculated as the skeletal muscle index (SMI), was measured using cross-sectional computed tomography (CT) scans preoperatively and then 1, 2, and 3 years after gastrectomy. RESULTS: Sarcopenia developed from 2 years onwards in all the patients who underwent TG. The SMI and sarcopenia prevalence after gastrectomy deteriorated over time. Multivariate analysis revealed that TG and PG were significant risk factors for skeletal muscle loss in postoperative years 1 and 3. A decrease in the SMI after TG or PG was most remarkable in elderly patients. CONCLUSIONS: The type of gastrectomy affects skeletal muscle loss in the long term. Elderly patients who undergo TG or PG are at high risk of severe skeletal muscle loss.

Cause of mortality and sarcopenia in patients with idiopathic pulmonary fibrosis receiving antifibrotic therapy.

BACKGROUND AND OBJECTIVE: Recent research has highlighted the fundamental role of sarcopenia, characterized by loss of skeletal muscle mass and strength, with a risk of poor outcomes. AFT preserves lung function by preventing the annual decline in FVC and is associated with improved outcomes in patients with IPF. However, altered cause of death and prognostic implications of sarcopenia in patients with IPF receiving AFT remain unknown. METHODS: This study comprised two cohorts of patients with IPF receiving AFT, historical cohort of IPF patients without AFT and controls. The cause of mortality was compared with a historical cohort. Sarcopenia was assessed by measuring the ESMCSA and ESMMA via CT. RESULTS: Patients with IPF had smaller ESMCSA and lower ESMMA but similar BMI than controls, suggesting patients with IPF had skeletal muscle loss without any obvious body weight loss. The most common cause of mortality in patients receiving AFT was chronic respiratory failure, accounting for approximately 60%, and decreased proportions of LC were found. Subsequently, low ESMCSA was an independent prognostic factor associated with worse survival rates. Furthermore, combined assessment of ESMCSA , %FVC predicted and BMI values provided clear prognostic distinction. CONCLUSION: Patients with IPF receiving AFT showed skeletal muscle loss without obvious weight loss. These patients mostly died by chronic respiratory failure, and skeletal muscle wasting has prognostic significance, suggesting that preventing sarcopenia as well as preserving lung function are important for managing these patients.

Impact of preoperative nutritional support and rehabilitation therapy in patients undergoing pancreaticoduodenectomy.

BACKGROUND: Sarcopenia is closely associated with morbidity after pancreatic surgery. We investigated the impact of preoperative nutritional support and rehabilitation on patients undergoing pancreaticoduodenectomy. METHODS: This was a retrospective analysis of 101 patients who underwent pancreaticoduodenectomy. Skeletal muscle (SM) loss was defined using the SM index (cutoff level: 42 cm2/m2 in men and 38 cm2/m2 in women). A total of 33 and 30 patients received preoperative nutrition and prehabilitation, respectively. The neutrophil-to-lymphocyte ratio (NLR), Prognostic Nutritional Index (PNI), and modified Glasgow Prognostic Score (mGPS) values were calculated during the first visit and immediately before surgery. RESULTS: SM loss was present in 65 of 101 patients and was significantly correlated with female sex, older age, lower body mass index, and low PNI. Preoperative nutritional support and prehabilitation prevented the decrease in PNI values in patients with SM loss. The NLR significantly improved in patients with SM loss who received nutritional support and prehabilitation. In patients with SM loss, the lack of preoperative nutrition and prehabilitation was an independent risk factor for postoperative pancreatic fistula. CONCLUSIONS: Preoperative nutritional support and prehabilitation may reduce the incidence of pancreatic fistula in patients with SM loss and improve the surgical outcomes of patients undergoing pancreaticoduodenectomy.

Skeletal muscle loss after laparoscopic gastrectomy assessed by measuring the total psoas area.

PURPOSE: Skeletal muscle loss after gastrectomy can worsen patients' quality of life and prognosis. Laparoscopic gastrectomy is less invasive than open gastrectomy and has become commonly performed. However, the degree of skeletal muscle loss after laparoscopic procedures remains unclear. We herein report the degree and risk factors of psoas muscle loss after laparoscopic gastrectomy for gastric cancer. METHODS: The total psoas area (TPA) on computed tomography of 50 consecutive patients who underwent laparoscopic total gastrectomy (LTG) and 167 consecutive patients who underwent laparoscopic distal gastrectomy (LDG) for gastric cancer was retrospectively evaluated at one postoperative year. The TPA loss was compared between LDG and LTG and univariate and multivariate analyses were performed to identify the risk factors for TPA loss > 10%. RESULTS: The median TPA decrease rate was 5.9% in the LDG group and 15.6% in the LTG group. LTG and postoperative respiratory complications were independent factors associated with a severe TPA loss of > 10%. In the LTG group, no independent factors were identified in a multivariate analysis. In the LDG group, postoperative complications were identified as an independent risk factor for TPA loss > 10%. CONCLUSIONS: Laparoscopic gastrectomy leads to postoperative TPA loss, especially in patients who underwent LTG and had postoperative respiratory complications. Postoperative complications after LDG were also a risk factor for TPA loss.

Perioperative body composition changes in the multimodal treatment of gastrointestinal cancer.

Surgical resection and perioperative adjuvant therapy are widely accepted standard treatments for gastrointestinal cancer. However, body composition changes, such as weight loss and skeletal muscle loss, are unavoidable during these treatments. Several studies have shown that perioperative body composition changes are affected by multimodal treatment for gastrointestinal cancer. This review summarizes the background, current status, and future perspectives of perioperative body composition changes in the multimodal treatment of gastrointestinal cancer. Recent studies have described the body composition changes observed in the early period after surgery and during adjuvant therapy. Changes in the body composition might affect adjuvant chemotherapy toxicity after surgery and postoperative complications after neoadjuvant therapy. The mechanisms underlying body composition changes during multimodal therapy are multifactorial and include systemic inflammation, reduced nutrient intake, and physical inactivity. Several approaches have been tested to maintain the body composition, and especially prevent skeletal muscle wasting, during multimodal therapy. Although the ideal approach for managing body composition changes in gastrointestinal cancer patients remains unclear, recent studies support the combination of multiple approaches rather than a single approach.

Skeletal muscle loss during systemic chemotherapy for colorectal cancer indicates treatment response: a pooled analysis of a multicenter clinical trial (KSCC 1605-A).

BACKGROUND: Sarcopenia or degenerative loss of skeletal muscle mass is related to poor prognosis in patients with cancer. This study aimed to clarify the clinical significance of skeletal muscle loss (SML) during chemotherapy for metastatic colorectal cancer (mCRC). METHODS: A total of 249 patients who were secondarily registered in a pooled database of mCRC patients with the first-line systemic chemotherapy and prospectively enrolled in six clinical trials of Kyushu Study Group of Clinical Cancer were included in this study. Skeletal muscle area was calculated from computed tomography images before and 3 and 6 months after treatment. Baseline sarcopenia and SML (cut-off value = 9%) were evaluated. RESULTS: Baseline sarcopenia was observed in 135 of 219 patients who were evaluated before treatment. They tended to be male; older; and have lower body mass index, lower visceral and subcutaneous fat contents, and a lower waist circumference (P < 0.01); however, baseline sarcopenia was not associated with prognosis. SML at 3 months was associated with an incidence of adverse events (P = 0.01), poor objective response rate (ORR) (P < 0.01), and poor progression-free survival (PFS) (P = 0.03), and it was an independent predictive factor for poor ORR (P < 0.01) and PFS (P = 0.04). CONCLUSION: SML at 3 months after systemic chemotherapy for mCRC was associated with poor treatment response. Thus, clarifying the importance of SML prevention guarantees a more effective chemotherapy.

Skeletal Muscle Loss during Neoadjuvant Chemotherapy Is an Independent Risk Factor for Postoperative Infectious Complications in Patients with Advanced Esophageal Cancer.

OBJECTIVE: Neoadjuvant therapy followed by surgery has been the standard treatment for advanced esophageal cancer. Severe toxicities may influence body composition, including skeletal muscle mass, and increase postoperative complications. The purpose of this study was to evaluate the influence of sarcopenia, changes in body composition, and adverse events during neoadjuvant chemotherapy (NACT) on postoperative complications in esophageal cancer patients. METHODS: A total of 83 patients with esophageal cancer undergoing NACT followed by esophagectomy were included. Body composition was assessed before chemotherapy and before esophagectomy. The relationships between postoperative infectious complications and sarcopenia, changes in body composition, and adverse events during NACT were investigated. RESULTS: Univariate analysis revealed that skeletal muscle loss during NACT, but not preoperative sarcopenia, was significantly higher in the complication (+) group. Febrile neutropenia tended to occur frequently in the complication (+) group. Multivariate analysis demonstrated that skeletal muscle loss was the only factor significantly associated with infectious complications (p = 0.029). Among adverse events, febrile neutropenia was significantly associated with a decrease in skeletal muscle mass. CONCLUSION: Loss of skeletal muscle mass during NACT was a significant risk factor for postoperative infectious complications in patients with esophageal cancer. Prevention of severe adverse events may reduce postoperative infectious complications.

Rapidly declining skeletal muscle mass predicts poor prognosis of hepatocellular carcinoma treated with transcatheter intra-arterial therapies.

BACKGROUND: The impact of sarcopenia on the prognosis of patients with hepatocellular carcinoma (HCC) who receive transcatheter intra-arterial therapies, including transcatheter arterial chemoembolization and transcatheter arterial infusion chemotherapy, remains unclear. We investigated the prognostic value of skeletal muscle loss (SML) stratified by cutoffs for sarcopenia and rate of change in skeletal muscle mass over 6 months. METHODS: We retrospectively evaluated 102 patients with HCC treated with transcatheter intra-arterial therapies between 2005 and 2015. Computed tomography images of the third lumbar vertebra (L3) were analyzed to obtain the skeletal muscle area normalized for the height squared, defined as the skeletal muscle index at L3 (L3 SMI), before and 6 months after treatment. Low or high SMI was defined using cutoff values of 42 cm2/m2 in men and 38 cm2/m2 in women. The rate of change in skeletal muscle mass (ΔL3 SMI) over 6 months was calculated. Overall survival (OS) was compared in groups classified by baseline L3 SMI and ΔL3 SMI; prognostic significance was assessed with univariate and multivariate analyses, using Cox proportional hazards models. RESULTS: OS did not differ significantly between groups with low (n = 31) and high (n = 71) SMI at baseline (P = 0.172), but OS was significantly poorer in patients with SML (n = 41), defined as ΔL3 SMI < - 4.6% over 6 months than in those without SML (n = 61, P = 0.018). On multivariate analysis, SML (hazard ratio [HR], 1.675; 95% confidence interval [CI], 1.031-2.721; P = 0.037), serum alpha-fetoprotein ≥20 ng/mL (HR, 2.550; 95% CI, 1.440-4.515; P = 0.001), and maximum tumor diameter ≥ 30 mm (HR, 1.925; 95% CI, 1.166-3.179; P = 0.010) were independent predictors of poor OS. Baseline L3 SMI was not significantly associated with OS (HR, 1.405; 95% CI, 0.861-2.293; P = 0.174). CONCLUSIONS: ΔL3 SMI was an independent prognostic factor in patients with HCC treated with transcatheter intra-arterial therapies. Further study is required to reveal whether prevention of skeletal muscle depletion might be a new therapeutic strategy to contribute to improved clinical outcomes in patients with HCC.

Inflammaging and Skeletal Muscle: Can Protein Intake Make a Difference?

Inflammaging is the chronic low-grade inflammatory state present in the elderly, characterized by increased systemic concentrations of proinflammatory cytokines. It has been shown that inflammaging increases the risk of pathologic conditions and age-related diseases, and that it also has been associated with increased skeletal muscle wasting, strength loss, and functional impairments. Experimental evidence suggests that the increased concentrations of proinflammatory cytokines and primary tumor necrosis factor α observed in chronic inflammation lead to protein degradation through proteasome activation and reduced skeletal muscle protein synthesis (MPS) via protein kinase B/Akt downregulation. Dairy and soy proteins contain all the essential amino acids, demonstrate sufficient absorption kinetics, and include other bioactive peptides that may offer nutritional benefits, in addition to those of stimulating MPS. Whey protein has antioxidative effects, primarily because of its ability to enhance the availability of reduced glutathione and the activity of the endogenous antioxidative enzyme system. Soy protein and isoflavone-enriched soy protein, meanwhile, may counteract chronic inflammation through regulation of the nuclear transcription factor κB signaling pathway and cytokine production. Although evidence suggests that whey protein, soy protein, and isoflavone-enriched soy proteins may be promising nutritional interventions against the oxidative stress and chronic inflammation present in pathologic conditions and aging (inflammaging), there is a lack of information about the anabolic potential of dietary protein intake and protein supplementation in elderly people with increased systemic inflammation. The antioxidative and anti-inflammatory effects, as well as the anabolic potential of protein supplementation, should be further investigated in the future with well-designed clinical trials focusing on inflammaging and its associated skeletal muscle loss.

Therapeutic applications of biological macromolecules and scaffolds for skeletal muscle regeneration: A review.

Skeletal muscle (SM) mass and strength maintenance are important requirements for human well-being. SM regeneration to repair minor injuries depends upon the myogenic activities of muscle satellite (stem) cells. However, losses of regenerative properties following volumetric muscle loss or severe trauma or due to congenital muscular abnormalities are not self-restorable, and thus, these conditions have major healthcare implications and pose clinical challenges. In this context, tissue engineering based on different types of biomaterials and scaffolds provides an encouraging means of structural and functional SM reconstruction. In particular, biomimetic (able to transmit biological signals) and several porous scaffolds are rapidly evolving. Several biological macromolecules/biomaterials (collagen, gelatin, alginate, chitosan, and fibrin etc.) are being widely used for SM regeneration. However, available alternatives for SM regeneration must be redesigned to make them more user-friendly and economically feasible with longer shelf lives. This review aimed to explore the biological aspects of SM regeneration and the roles played by several biological macromolecules and scaffolds in SM regeneration in cases of volumetric muscle loss.

Risk Factors Associated With Perioperative Skeletal Muscle Loss in Patients With Colorectal Cancer.

BACKGROUND/AIM: Postoperative changes in body composition, especially loss of muscle mass, often occur in gastrointestinal cancer patients. Few studies have reported perioperative changes in the body composition of patients with colorectal cancer. Therefore, this study aimed at clarifying changes in body composition during the perioperative period and identifying risk factors for skeletal muscle mass loss in patients with colorectal cancer. PATIENTS AND METHODS: This prospective observational study included 148 patients who underwent robot- or laparoscopic-assisted surgery for colorectal cancer. RESULTS: The rate of change in body composition at discharge was -6.25% for body fat, with a higher rate of decrease than that for skeletal muscle mass (-3.30%; p=0.0006) and body water mass (-2.66%; p=0.0001). Similarly, even at one month postoperatively, body fat mass (-8.05%) was reduced at a greater rate than skeletal muscle mass (-2.02% p=0.0001) and body water mass (-1.33% p=0.0001).The site-specific percent change in limb skeletal and trunk muscle mass at discharge was the greatest in the lower extremities at -5.37%, but one month after surgery, the upper extremities had the greatest change at -4.44%. The Prognostic Nutritional Index (PNI) influenced skeletal muscle mass loss at discharge [odds ratio (OR)=2.6; 95% confidence interval (CI)=1.30-5.58], while diabetes (OR=4.1; 95%CI=1.40-12.43) and ileostomy (OR=6.7; 95%CI=1.45-31.11) influenced skeletal muscle loss one month postoperatively. CONCLUSION: Preoperative and postoperative nutritional guidance/intervention and body part-specific rehabilitation should be provided to prevent skeletal muscle mass loss in patients with low PNI, diabetes, and those undergoing ileostomy.

Prognostic impact of muscle mass loss in elderly patients with oesophageal cancer receiving neoadjuvant chemoradiation therapy.

BACKGROUND: We aimed to identify the impact of muscle mass on locally advanced oesophageal cancer (LAEC) in elderly patients receiving neoadjuvant chemoradiation therapy (NACRT). METHODS: We reviewed the medical records of 345 patients diagnosed with LAEC who underwent NACRT and surgery. Physical variables, including height, weight, skeletal muscle mass, and laboratory values, were obtained before and after NACRT. Body mass index (BMI, kg/m2), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and prognostic nutritional index (PNI) were calculated as height/(weight)2, ANC/ALC, platelet count/ALC, and (10 × albumin + 0.05 × ALC), respectively. The cutoff for low muscle mass was 43.0 cm2/m2 for BMI below 25 kg/m2 and 53.0 cm2/m2 for BMI 25 kg/m2 or higher. The skeletal muscle index (SMI) was defined as skeletal muscle area/(height)2 (cm2/m2). The ΔSMI (%/50 days) was defined as (SMI after NACRT - SMI before NACRT)/interval (days) × 50 (days) to compare changes over the same period. The excessive muscle loss (EML) group was defined as patients with ΔSMI ≤-10% following NACRT. An elderly patient was defined as aged ≥65 years. The primary outcome measure was overall survival (OS). RESULTS: During a median follow-up of 32.8 months (range, 2.0-176.2), 192 patients died, with a median OS of 50.2 months. Elderly patients did not show inferior OS (young vs. elderly, 57.7% vs. 54.0% at 3 years, P = 0.247). 71.0% and 87.2% of all patients had low muscle mass before and after NACRT, respectively, which was not associated with OS (P = 0.270 and P = 0.509, respectively). Inflammatory (NLR and PLR) and nutritional index (PNI) values or their changes did not correlate with OS. However, the EML group had worse OS (41.6% vs. 63.2% at 3 years, P < 0.0001). In the multivariate analysis, EML was also a significant prognostic factor for OS. In the subgroup analysis by age, EML was a strong prognostic factor for OS in the elderly group. The 3-year OS was 36.8% in the EML group and 64.9% in the non-EML group (P < 0.0001) in elderly patients, and 47.4% and 62.1% (P = 0.063) in the young patients. In multivariate analysis of each subgroup, EML remained prognostic only in the elderly group (P = 0.008). CONCLUSIONS: EML may be strongly associated with a deteriorated OS in elderly patients undergoing NACRT, followed by surgery for LAEC. The strategies for decreasing muscle loss in these patients should be investigated.

A Comparative Biochemical Study Between L-Carnosine and ß-Alanine in Amelioration of Hypobaric Hypoxia-Induced Skeletal Muscle Protein Loss.

Rathor, Richa, Sukanya Srivastava, and Geetha Suryakumar. A comparative biochemical study between L-carnosine and ß-alanine in amelioration of hypobaric hypoxia-induced skeletal muscle protein loss. High Alt Med Biol. 24:302-311, 2023. Background: Carnosine (CAR; ß-alanyl-L-histidine), a biologically active dipeptide is known for its unique pH-buffering capacity, metal chelating activity, and antioxidant and antiglycation property. ß-Alanine (ALA) is a nonessential amino acid and used to enhance performance and cognitive functions. Hypobaric hypoxia (HH)-induced muscle protein loss is regulated by multifaceted signaling pathways. The present study investigated the beneficial effects of CAR and ALA against HH-associated muscle loss. Methodology: Simulated HH exposure was performed in an animal decompression chamber. Gastric oral administration of CAR (50 mg·kg-1) and ALA (450 mg·kg-1) were given daily for 3 days and at the end of the treatment, hindlimb skeletal muscle tissue was excised for western blot and biochemical assays. Results: Cosupplementation of CAR and ALA alone was able to ameliorate the hypoxia-induced inflammation, oxidative stress (FOXO), ER stress (GRP-78), and atrophic signaling (MuRF-1) in the skeletal muscles. Creatinine phospho kinase activity and apoptosis were also decreased in CAR- and ALA-supplemented rats. However, CAR showed enhanced protection in HH-induced muscle loss as CAR supplementation was able to enhance protein concentration, body weight, and decreased the protein oxidation and ALA administration was not able to restore the same. Conclusions: Hence, the present comprehensive study supports the fact that CAR (50 mg·kg-1) is more beneficial as compared with ALA (450 mg·kg-1) in ameliorating the hypoxia-induced skeletal muscle loss.